Epoxy compounds are reacted with various curing agents and curing catalysts to produce cured products. These epoxy compounds are useful as components of coating agents, adhesives, inks or sealants or intermediates for producing compounds which are useful in the various final applications such as pharmaceutical agents or medical products, and it has thus been desired to develop a method for supplying such epoxy compounds which is efficient and environmentally-friendly as well as industrially valuable.
The main component of an epoxy resin that is industrially applicable is produced through a reaction of polyphenols and epichlorohydrin. Glycidyl compounds generated thereupon contain several thousand ppm of chemically bonded chlorine depending on the processing conditions. Chlorine-free epoxy resins have been desired in viewpoint of for example environmental issues or safety. In use for electronic materials in particular, chlorine has been regarded as problems because it causes corrosion of wiring or deterioration of insulating characteristics, resulting in the materials with less reliability, and therefore also in this regard, the epoxy compounds have been demanded to be decreased in the chlorine content.
As a method for producing an epoxy compound, a method is known, in which olefins are oxidized with peracids such as peracetic acid. However, this method has problems that peracids require careful handling, and epoxides are reacted with carboxylic acids presented in the reaction system thereby producing esters and the like, resulting in a decrease in the selectivity of the epoxides, and also that in production of an alicyclic epoxy compound regarded as having a high reactivity with acids, coexisting organic acids are easily reacted with epoxy groups produced in the presence of water, resulting in a decrease in the selectivity of the epoxides due to the ring-opening of the epoxy groups, and the post-treatments are troublesome. Therefore, a method has been attracting attention, which uses hydrogen peroxide as an oxidation agent, which is easy in handling and turns to water that is harmless after the reaction.
As a method for producing an epoxy compound from olefins using hydrogen peroxide, a method is known in which epoxidation is carried out by reacting olefins and a hydrogen peroxide solution with a halogenated hydrocarbon as a solvent using a catalyst such as polyacids (Patent Literature 1). This method, however, has problems concerning halogen impurities in the products and environmental load due to the use of the halogenated hydrocarbon.
Patent Literature 2 discloses a solid phase reaction system for oxidation comprising a mixture of a powdered solid catalyst support and a powdered solid catalyst for oxidation reaction, an organic compound and a hydrogen peroxide solution.